/**
 * Created with IntelliJ IDEA.
 * Description: 只出现一次的元素
 * Author:  LiuTao
 * Version: 1.0
 * Date:    2023-05-29  22:31
 */
public class Test1 {
    public static void main(String[] args) {
        int array[] = {1,2,3,2,1};
        int ans = 0;
        for(int i = 0; i < array.length;i++){
            ans = ans ^ array[i];
        }
        System.out.println(ans);
    }
}
